This invention relates to hoists, specifically to portable and mobile hoists. While many hoists available may accomplish the same task of article manipulation, they all include features which limit the scope of their use. For instance, some are designed to be anchored to a floor, wall or land vehicle. Others are very heavy and bulky, making them a less likely candidate to be used on flat commercial rooftops or in poorly accessible work areas. These limitations force many well designed hoists to be dismissed simply as the wrong tool for the job in situations where the work they accomplish is in demand.
For example, in the commercial HVAC service industry, technicians frequently replace refrigeration compressors and electric fan motors weighing in excess of two hundred pounds. Often, the units containing them are located upon flat rooftops, so an extension ladder, rope and a common hand truck are utilized to get the job done. If the compressor or fan motor is too heavy to safely lift, additional personnel or expensive crane rentals become the only safe and viable alternatives.
Typically, extension ladder hoists are be used to raise a load from the ground surface at the bottom of the ladder to the rooftop. A common hand truck is then used to transport the motor laterally across the roof surface to the air conditioner or air handling unit. However, once the technician arrives at the unit to be repaired, the load must be manually lifted and placed into its compartment, as well as getting the existing load out and carefully setting it down on the roof surface. These compartments are typically one to three feet above the roof surface, creating an unsafe lifting practice, often resulting in injury or property damage. Hence, a mechanical advantage for this and many other similar scenarios is greatly needed.